Update URL to the License

tools/esp8266/html/index.html

@@ -13,7 +13,7 @@
             function promptFunction() {
                 var Text = prompt("This project was started from https://www.mikrocontroller.net/topic/525778 this discussion.\n\n" + 
                 "The Hoymiles protocol was decrypted through the voluntary efforts of many participants. ahoy, among others, was developed based on this work. The project is licensed under an Open Source " + 
-                "License (https://www.gnu.de/documents/gpl-2.0.de.html) GNU General Public License v3.0.\n\n" + 
+                "License (https://github.com/lumapu/ahoy/blob/main/LICENSE) GNU General Public License v3.0.\n\n" + 
                 "The software was developed to the best of our knowledge and belief. Nevertheless, no liability can be accepted for a malfunction or guarantee loss of the inverter.\n\n" + 
                 "Ahoy is freely available. If you paid money for the software, you probably got ripped off.\n\nPlease type in 'YeS', you are accept our Disclaim.", "");
                 if (Text != "YeS")